Transcription factors and pattern formation in the developing lung.

During development of the respiratory tract embryonic cells are instructed to organize themselves along an axis and differentiate, such that proximal structures (trachea) greatly differ from those in distal alveoli. Pattern formation relates to this process of organization, and it is believed to be transcriptionally regulated in many developmental systems. Although the lung is the site of expression of many transcription factors, such as Hox, retinoid receptors, hepatocyte nuclear factors, and myc, among others, little information is available on how they influence lung pattern. Functional studies so far have directly implicated the product of the protooncogene N-myc and the retinoic acid receptors as transcriptional regulators of lung patterning, and it is likely that tissue-specific homeobox genes, such as the thyroid transcription factor-1, play an important role in distal lung formation. This review describes several aspects of transcription factors possibly involved in lung patterning, including structure, spatial distribution, and their putative functions.